Jet pump improvement



Dec. 31, 1963 J. J. MAITLEN JET PUMP IMPROVEMENT Filed Feb. 25, 1962 2 Sheets-Sheet 1 FIG-l INVENTOR.

JOHN J. MAITLEN ATTORNEYS Dec. 31, 1963 J. J. MAITLEN JET PUMP IMPROVEMENT 2 Sheets-Sheet 2 Filed Feb. 25, 1962 R m V m JOHN J. MAITLEN ATTORNEYS United States Patent of Ohio Filed Feb. 23, 1962, Ser. No. 175,880

2 Claims. (Cl. 103-103) This invention relates to jet pump constructions and is particularly concerned with an improvement therein pertaining to the more efficient separation of air from the liquid being pumped.

In the usual jet pump, in which there is an air separating chamber integral with the pump, and wherein the rotary impeller has an axial fiange that is closely surrounded by a neck formed on the shroud, or diffuser plate, there is a tendency for air to become entrained in the water in the air separation chamber. This becomes a problem when the casing or air separation chamber of a jet pump is filled with water and then the pump is started so that the pump will evacuate air entrapped in the suction line leading from the pump. Where an appreciable amount of air is to be removed, a condition is sometimes reached where a mixture of air and liquid is passed through the impeller and diffuser.

The liquid for the jet is supplied by the liquid pumped in this manner and is usually drawn off from the pump casing at a lower part thereof. However, on account of the rotation of the impeller, some separation of air from the water takes place about the inlet opening of the impeller and this can form an air ring surrounding the inlet neck of the impeller. This air is then entrapped within the pump casing and is not removed therefrom, leading to faulty operation of the pump and the distinct possibility of the neck or axial flange about the impeller inlet heating up and seizing on the neck or central aperture in the diffuser plate, particularly, during the starting process of such a pump.

The present invention proposes, particularly, an arrangement for eliminating the possibility of collecting a ring of air about the impeller inlet neck and insuring that, instead, as soon as there is a supply of water in the pump casing, the neck of the impeller will be surrounded by a film of water.

With the foregoing in mind, it will be apparent that a primary objective of the present invention is the provision of an arrangement in a jet pump for preventing an accumulation of a ring of air around the impeller neck, particularly, during the starting period of the pump.

Another objective of the present invention is the provision of an arrangement for insuring that there will be a film of liquid about the neck of the impeller of a centrifugal pump and, particularly, during the starting period thereof.

A still further objective of the present invention is the provision of an arrangement for insuring that the axial flange surrounding the inlet of the rotary impeller of a centrifugal pump will always be running inside a fluid film thereby eliminating the possibility of over-heating and seizing of the relatively rotatable pump parts at this point.

These and other objects and advantages of this invention will become more apparent upon reference to the following specification, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a vertical sectional view through a pump constructed according to the present invention;

FIGURE 2 is a fragmentary view drawn at greatly enlarged scale showing more in detail the construction of the pump according to this invention; and

FIGURE 3 is a transverse sectional view indicated by line 3-3 on FIGURE 1.

3,115,844 Patented Dec. 31, 1963 "ice Referring to the drawings somewhat more in detail, the pump arrangement illustrated comprises a casing 10 which has a portion 12 generally conically shaped and forming the back closure for the pump impeller 14. Pump impeller 14 is mounted on a drive shaft 16 that extends through a seal 18 surrounding the shaft and having an end portion carried in wall 12. Spaced from wall 12 is a second Wall 20 in which bearing means 22 is mounted for journaling shaft 16. Leftwardly of bearing means 22, shaft 16 is connected to or forms part of an electric drive motor.

The pump casing comprises another part 24 attached to part 10 and defining an air separation cavity 26. Mounted on the face of casing part 10 inside air separation chamber 26 is diffuser plate 28 which encloses the face of impeller 14 and also extends around the periphery thereof and receives the discharge from the pump impeller. Diffuser plate 28 is formed with passage means 30 forming the diffuser passages for transferring the liquid pumped from the periphery of the pump impeller into the air separation chamber.

The casing part 24 has a cylindrical portion 32 extending from the outer wall thereof inwardly and terminating in an annular portion 34 that surrounds an axially extending cylindrical flange 36 of diffuser plate 28. An O-ring seal 38 is disposed between the flange 36 of the diffuser plate and the inner end of cylindrical projection 32 to seal therebetween.

Cylindrical portion 32 forms the suction inlet leading to the impeller and may communicate at its outer end with a suction conduit, or there may be a jet pump mounted in cylindrical portion 32.

The pump impeller has an axially extending flange or neck portion 40 extending from the inlet thereof into the cylindrical opening or neck 42 of the diffuser plate. The neck portion of the impeller may consist of a metal sleeve 44 molded directly into the body of the impeller. There is a relatively close running fit between the neck of the impeller and the aforesaid opening in the diffuser plate and it is in connection with this particular region that the present invention is concerned.

This is the region in which an air layer is apt to be trapped and lead to over-heating or seizing of the impeller on the diffuser plate. According to the present invention, this is prevented by providing the cylindrical portion 42 of the diffuser plate with an annular groove 46 opening inwardly toward the metal sleeve 44 carried by the impeller. This annular groove communicates at the bottom by way of passage 48 with the lower portion of the air separation chamber 26. When the pump is operating, the water supplied to the air separation chamber tends to be solid water in the lower region of the air separation chamber with the air moving to the upper portion of the air separation chamber. Accordingly, there is a supply of water, and under pressure, from the air separation chamber through passage 48 into groove 46 and this establishes a liquid film about the neck of the impeller shortly after the pump commences to operate and maintains this film as long as the pump is operating. This liquid film will drive air from the space between the neck of the impeller and the diffuser plate and Will also cool and lubricate this region so that the aforementioned over-heating and the possibility of seizure of the impeller on the diffuser plate is eliminated.

The pump operates more efiiciently on account of the provision of this liquid film and clearances can be maintained somewhat closer than has heretofore been possible.

The air that flows across the ring fit from the discharge side of the impeller passes to the suction side and is thus recirculated through the pump. This reduces the amount of air that can be removed from the suction line and interferes with the operation of the pump, including making for a long priming period.

In practice, a particularly effective arrangement of the present invention is had when the area of the orifices equals the area of the annular clearance area between the impeller and the diffuser plate at the running fit.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a centrifugal pump; an impeller casing comprising an impeller chamber and an air separating chamber, a drive shaft mounted for rotation and extending into said impeller chamber, a rotary impeller on said drive shaft, said impeller casing having a rear cylindrical portion extending inwardly and terminating in an annular portion, said impeller having a cylindrical flange extending axially and centrally thereof and forming an inlet passage to the impeller, a diffuser plate which substantially encloses said impeller and which abuts against said rear annular portion, said diffuser plate comprising a cylindrical neck into which said flange extends, an inlet conduit extending through said air separating chamber and communicating with said cylindrical neck through which liquid is delivered to said impeller, said diff-user plate having an annular groove disposed around the inside of said neck and opening inwardly toward said cylindrical flange, and a radial bore in the lower portion of said neck and leading from said annular groove and communicating with said air separating chamber through which liquid under pressure is supplied from said air separating chamber to said annular groove to establish a liquid film about said neck during operation of said pump to cool and lubricate the same.

2. In a centrifugal pump; an impeller casing part comprising an impeller chamber and an air separating chamber, a drive shaft mounted for rotation and extending into said impeller chamber, a rotary plastic impeller on said drive shaft, said impeller casing part having a cylindrical rear wall portion extending inwardly and terminating in an annular portion, said impeller having a cylindrical flange extending axially and centrally thereof and forming an inlet passage to the impeller, a plastic dilfuser plate which substantially encloses said impeller and which abuts against said cylindrical wall portion, said diffuser plate comprising a cylindrical neck portion into which said cylindrical flange, of the impeller extends, a reinforcing metal sleeve embedded in the flange of said plastic impeller, an inlet conduit extending through said air separating chamber. and communicating with said neck portion through which liquid is delivered to said impeller, said diffuser plate having an annular groove disposed around the inside of said neck and opening inwardly toward said cylindrical flange, and a radial bore in the lower portion of said neck portion and leading from said annular groove and communicating with said air separating chamber through which liquid under pressure is supplied during operation of the pump to said annular groove to establish a liquid film about said neck whereby the impeller and diffuser plate are cooled and lubricated as the pump is operated.

References Cited in the file of this patent UNITED STATES PATENTS 2,282,765 Mann, May 12, 1942 2,631,539 Wolfeet al. Mar, 17, 1953 2,677,327 MacNeille et al.. May 4, 1954 2,736,265 Higgins Feb. 28, 1956 2,811,109 Brill et al. Oct. 29, 195.7 3,063,377 Stanley et al.. Nov. 13, 1962 FOREIGN PATENTS 1,059,878 France Nov. 18, 1953 

1. IN A CENTRIFUGAL PUMP; AN IMPELLER CASING COMPRISING AN IMPELLER CHAMBER AND AN AIR SEPARATING CHAMBER, A DRIVE SHAFT MOUNTED FOR ROTATION AND EXTENDING INTO SAID IMPELLER CHAMBER, A ROTARY IMPELLER ON SAID DRIVE SHAFT, SAID IMPELLER CASING HAVING A REAR CYLINDRICAL PORTION EXTENDING INWARDLY AND TERMINATING IN AN ANNULAR PORTION, SAID IMPELLER HAVING A CYLINDRICAL FLANGE EXTENDING AXIALLY AND CENTRALLY THEREOF AND FORMING AN INLET PASSAGE TO THE IMPELLER, A DIFFUSER PLATE WHICH SUBSTANTIALLY ENCLOSES SAID IMPELLER AND WHICH ABUTS AGAINST SAID REAR ANNULAR PORTION, SAID DIFFUSER PLATE COMPRISING A CYLINDRICAL NECK INTO WHICH SAID FLANGE EXTENDS, AN INLET CONDUIT EXTENDING THROUGH SAID AIR SEPARATING CHAMBER AND COMMUNICATING WITH SAID CYLINDRICAL NECK THROUGH WHICH LIQUID IS DELIVERED TO SAID IMPELLER, SAID DIFFUSER PLATE HAVING AN ANNULAR GROOVE DISPOSED AROUND THE INSIDE OF SAID NECK AND OPENING INWARDLY TOWARD SAID CYLINDRICAL FLANGE, AND A RADIAL BORE IN THE LOWER PORTION OF SAID NECK AND LEADING FROM SAID ANNULAR GROOVE AND 